Weiwei Zhu, Di Li, Rui Luo, Chenchen Miao, Bing Zhang, Laura Spitler, Duncan Lorimer, Michael Kramer, David Champion, Youling Yue, Andrew Cameron, Marilyn Cruces, Ran Duan, Yi Feng, Jun Han, George Hobbs, Chenhui Niu, Jiarui Niu, Zhichen Pan, Lei Qian, Dai Shi, Ningyu Tang, Pei Wang, Hongfeng Wang, Mao Yuan, Lei Zhang, Xinxin Zhang, Shuyun Cao, Li Feng, Hengqian Gan, Long Gao, Xuedong Gu, Minglei Guo, Qiaoli Hao, Lin Huang, Menglin Huang, Peng Jiang, Chengjin Jin, Hui Li, Qi Li, Qisheng Li, Hongfei Liu, Gaofeng Pan, Bo Peng, Hui Qian, Xiangwei Shi, Jinyuo Song, Liqiang Song, Caihong Sun, Jinghai Sun, Hong Wang, Qiming Wang, Yi Wang, Xiaoyao Xie, Jun Yan, Li Yang, Shimo Yang, Rui Yao, Dongjun Yu, Jinglong Yu, Chengmin Zhang, Haiyan Zhang, Shuxin Zhang, Xiaonian Zheng, Aiying Zhou, Boqin Zhu, Lichun Zhu, Ming Zhu, Wenbai Zhu, Yan Zhu
Apr 29, 2020·astro-ph.HE·PDF We report the discovery of a highly dispersed fast radio burst, FRB~181123, from an analysis of $\sim$1500~hr of drift-scan survey data taken using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulse has three distinct emission components, which vary with frequency across our 1.0--1.5~GHz observing band. We measure the peak flux density to be $>0.065$~Jy and the corresponding fluence $>0.2$~Jy~ms. Based on the observed dispersion measure of 1812~cm$^{-3}$~pc, we infer a redshift of $\sim 1.9$. From this, we estimate the peak luminosity and isotropic energy to be $\lesssim 2\times10^{43}$~erg~s$^{-1}$ and $\lesssim 2\times10^{40}$~erg, respectively. With only one FRB from the survey detected so far, our constraints on the event rate are limited. We derive a 95\% confidence lower limit for the event rate of 900 FRBs per day for FRBs with fluences $>0.025$~Jy~ms. We performed follow-up observations of the source with FAST for four hours and have not found a repeated burst. We discuss the implications of this discovery for our understanding of the physical mechanisms of FRBs.
Lei Zhang, Di Li, George Hobbs, Crispin H. Agar, Richard N. Manchester, Patrick Weltevrede, William A. Coles, Pei Wang, Weiwei Zhu, Zhigang Wen, Jianping Yuan, Andrew D. Cameron, Shi Dai, Kuo Liu, Qijun Zhi, Chenchen Miao, Mao Yua, Shuyun Cao, Li Feng, Hengqian Gan, Long Gao, Xuedong Gu, Minglei Guo, Qiaoli Hao, Lin Huang, Peng Jiang, Chengjin Jin, Hui Li, Qi Li, Qisheng Li, Hongfei Liu, Gaofeng Pan, Zhichen Pan, Bo Peng, Hui Qian, Lei Qian, Xiangwei Shi, Jinyou Song, Liqiang Song, Caihong Sun, Jinghai Sun, Hong Wang, Qiming Wang, Yi Wang, Xiaoyao Xie, Jun Yan, Li Yang, Shimo Yang, Rui Yao, Dongjun Yu, Jinglong Yu, Youling Yue, Chengmin Zhang, Haiyan Zhang, Shuxin Zhang, Xiaonian Zheng, Aiying Zhou, Boqin Zhu, Lichun Zhu, Ming Zhu, Wenbai Zhu, Yan Zhu
Apr 11, 2019·astro-ph.HE·PDF We describe PSR J1926-0652, a pulsar recently discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive single-pulse detections from FAST and long-term timing observations from the Parkes 64-m radio telescope, we probed phenomena on both long and short time scales. The FAST observations covered a wide frequency range from 270 to 800 MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at least four profile components, short-term nulling lasting from 4 to 450 pulses, complex subpulse drifting behaviours and intermittency on scales of tens of minutes. While the average band spacing P3 is relatively constant across different bursts and components, significant variations in the separation of adjacent bands are seen, especially near the beginning and end of a burst. Band shapes and slopes are quite variable, especially for the trailing components and for the shorter bursts. We show that for each burst the last detectable pulse prior to emission ceasing has different properties compared to other pulses. These complexities pose challenges for the classic carousel-type models.
Kai Zhang, Jingwen Wu, Di Li, Marko Krčo, Lister Staveley-Smith, Ningyu Tang, Lei Qian, Mengting Liu, Chengjin Jin, Youling Yue, Yan Zhu, Hongfei Liu, Dongjun Yu, Jinghai Sun, Gaofeng Pan, Hui Li, Hengqian Gan, Rui Yao
Mar 15, 2019·astro-ph.GA·PDF The Five-hundred-meter Aperture Spherical radio Telescope(FAST) is expected to complete its commissioning in 2019. FAST will soon begin the Commensal Radio Astronomy FasT Survey(CRAFTS), a novel and unprecedented commensal drift scan survey of the entire sky visible from FAST. The goal of CRAFTS is to cover more than 20000 $deg^{2}$ and reach redshift up to about 0.35. We provide empirical measurements of the beam size and sensitivity of FAST across the 1.05 to 1.45 GHz frequency range of the FAST L-band Array of 19-beams(FLAN). Using a simulated HI-galaxy catalogue based on the HI Mass Function(HIMF), we estimate the number of galaxies that CRAFTS may detect. At redshifts below 0.35, over $6\, \times \, 10^{5}$ HI galaxies may be detected. Below the redshift of 0.07, the CRAFTS HIMF will be complete above a mass threshold of $10^{9.5}\,M_{\odot}$. FAST will be able to investigate the environmental and redshift dependence of the HIMF to an unprecedented depth, shedding light onto the missing baryon and missing satellite problems.
Ningyu Tang, Di Li, Pei Zuo, Lei Qian, Tie Liu, Yuefang Wu, Marko Krčo, Mengting Liu, Youling Yue, Yan Zhu, Hongfei Liu, Dongjun Yu, Jinghai Sun, Peng Jiang, Gaofeng Pan, Hui Li, Hengqian Gan, Rui Yao, Shu Liu, FAST Collaboration
We present a pilot HI survey of 17 Planck Galactic Cold Clumps (PGCCs) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). HI Narrow Self-Absorption (HINSA) is an effective method to detect cold HI being mixed with molecular hydrogen H$_2$ and improves our understanding of the atomic to molecular transition in the interstellar medium. HINSA was found in 58\% PGCCs that we observed. The column density of HINSA was found to have an intermediate correlation with that of $^{13}$CO, following $\rm log( N(HINSA)) = (0.52\pm 0.26) log(N_{^{13}CO}) + (10 \pm 4.1) $. HI abundance relative to total hydrogen [HI]/[H] has an average value of $4.4\times 10^{-3}$, which is about 2.8 times of the average value of previous HINSA surveys toward molecular clouds. For clouds with total column density N$\rm_H >5 \times 10^{20}$ cm$^{-2}$, an inverse correlation between HINSA abundance and total hydrogen column density is found, confirming the depletion of cold HI gas during molecular gas formation in more massive clouds. Nonthermal line width of $^{13}$CO is about 0-0.5 km s$^{-1}$ larger than that of HINSA. One possible explanation of narrower nonthermal width of HINSA is that HINSA region is smaller than that of $^{13}$CO. Based on an analytic model of H$_2$ formation and H$_2$ dissociation by cosmic ray, we found the cloud ages to be within 10$^{6.7}$-10$^{7.0}$ yr for five sources.
Yingjie Jing, Jie Wang, Chen Xu, Ziming Liu, Qingze Chen, Tiantian Liang, Jinlong Xu, Yixian Cao, Jing Wang, Huijie Hu, Chuan-Peng Zhang, Qi Guo, Liang Gao, Mei Ai, Hengqian Gan, Xuyang Gao, Jinlin Han, Ligang Hou, Zhipeng Hou, Peng Jiang, Xu Kong, Fujia Li, Zerui Liu, Li Shao, Hengxing Pan, Jun Pan, Lei Qian, Jinghai Sun, Ningyu Tang, Qingliang Yang, Bo Zhang, Zhiyu Zhang, Ming Zhu
Jan 30, 2024·astro-ph.GA·PDF The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has the largest aperture and a 19-beam L-band receiver, making it powerful for investigating the neutral hydrogen atomic gas (HI) in the universe. We present HiFAST (https://hifast.readthedocs.io), a dedicated, modular, and self-contained calibration and imaging pipeline for processing the HI data of FAST. The pipeline consists of frequency-dependent noise diode calibration, baseline fitting, standing wave removal using an FFT-based method, flux density calibration, stray radiation correction, and gridding to produce data cubes. These modules can be combined as needed to process the data from most FAST observation modes: tracking, drift scanning, On-The-Fly mapping, and most of their variants. With HiFAST, the RMS noises of the calibrated spectra from all 19 beams were only slightly (~ 5%) higher than the theoretical expectation. The results for the extended source M33 and the point sources are consistent with the results from Arecibo. The moment maps (0,1 and 2) of M33 agree well with the results from the Arecibo Galaxy Environment Survey (AGES) with a fractional difference of less than 10%. For a common sample of 221 sources with signal-to-noise ratio S/N >10 from the Arecibo Legacy Fast ALFA (ALFALFA) survey, the mean value of fractional difference in the integrated flux density, $S_{\mathrm{int}}$, between the two datasets is approximately 0.005 %, with a dispersion of 15.4%. Further checks on the integrated flux density of 23 sources with seven observations indicate that the variance in the flux density of the source with luminous objects ($S_\mathrm{int}$ $ > 2.5$ Jy km s$^{-1}$) is less than 5%. Our tests suggest that the FAST telescope, with the efficient, precise, and user-friendly pipeline HiFAST, will yield numerous significant scientific findings in the investigation of the HI in the universe.
Peng Jiang, Youling Yue, Hengqian Gan, Rui Yao, Hui Li, Gaofeng Pan, Jinghai Sun, Dongjun Yu, Hongfei Liu, Ningyu Tang, Lei Qian, Jiguang Lu, Jun Yan, Bo Peng, Shuxin Zhang, Qiming Wang, Qi Li, Di Li
Mar 15, 2019·astro-ph.IM·PDF The Five-hundred-meter Aperture Spherical radio Telescope (FAST) was completed with its main structure installed on September 25, 2016, after which it entered the commissioning phase. This paper aims to introduce the commissioning progress of the FAST over the past two years. To improve its operational reliability and ensure effective observation time, FAST has been equipped with a real-time information system for the active reflector system and hierarchical commissioning scheme for the feed support system, which ultimately achieves safe operation of the two systems. For meeting the high-performance indices, a high-precision measurement system was set up based on the effective control methods that were implemented for the active reflector system and feed support system. Since the commissioning of the FAST, a low-frequency ultra-wideband receiver and 19-beam 1.05-1.45 GHz receiver have been mainly used. Telescope efficiency, pointing accuracy, and system noise temperature were completely tested and ultimately achieved the acceptance indices of the telescope. The FAST has been in the process of national acceptance preparations and has begun to search for pulsars. In the future, it will still strive to improve its capabilities and expand its application prospects.
Lei Qian, Zhichen Pan, Di Li, George Hobbs, Weiwei Zhu, Pei Wang, Zhijie Liu, Youling Yue, Yan Zhu, Hongfei Liu, Dongjun Yu, Jinghai Sun, Peng Jiang, Gaofeng Pan, Hui Li, Hengqian Gan, Rui Yao, Xiaoyao Xie, Fernando Camilo, Andrew Cameron, Lei Zhang, Shen Wang, FAST Project
Mar 15, 2019·astro-ph.IM·PDF To assist with the commissioning (Jiang et al. 2019) of the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we performed a pulsar search, with the primary goal of developing and testing the pulsar data acquisition and processing pipelines. We tested and used three pipelines, two (P1 and P2 hereafter) searched for the periodic signature of pulsars whereas the other one was used to search for bright single pulses (P3 hereafter). A pulsar candidate was discovered in the observation on the 22nd August, 2017, and later confirmed by the Parkes radio telescope on the 10th September, 2017. This pulsar, named PSR J1900-0134, was the first pulsar discovered by FAST. The pulsar has a pulse period of 1.8 s and a dispersion measure (DM) of 188\,pc\,cm$^{-3}$.
Jiale Zhang, Hui Tian, Stefano Bellotti, Tianqi Cang, Joseph R. Callingham, Harish K. Vedantham, Bin Chen, Sijie Yu, Philippe Zarka, Corentin K. Louis, Peng Jiang, Hongpeng Lu, Yang Gao, Jinghai Sun, Hengqian Gan, Hui Li, Chun Sun, Zheng Lei, Menglin Huang
Oct 20, 2025·astro-ph.SR·PDF Detecting coherent radio bursts from nearby M dwarfs provides opportunities for exploring their magnetic activity and interaction with orbiting exoplanets. However, it remains uncertain if the emission is related to flare-like activity similar to the Sun or magnetospheric process akin to magnetized planets. Using observations (1.0 - 1.5 GHz) taken by the Five-hundred-meter Aperture Spherical radio Telescope, we found a type of millisecond-scale radio bursts with exceptionally high frequency drift rates ($\sim 8\;\rm{GHz\;s^{-1}}$) from an active M dwarf, AD Leo. The ultrafast drift rates point to a source region with a notably low magnetic scale height ($<0.15\; r_\star$, $r_\star$ as the stellar radius), a feature not expected in a commonly assumed dipole-like global field but highly possible in localized strong-field structures, i.e. starspots. Our findings suggest that a concentrated magnetic field above starspots could be responsible for some of the most intense radio bursts from M dwarfs, supporting a solar-like electron acceleration mechanism.
Lei Qian, Rui Yao, Jinghai Sun, Jinlong Xu, Zhichen Pan, Peng Jiang
Nov 27, 2020·astro-ph.IM·PDF FAST is the largest single-dish radio telescope in the world. The characteristics of FAST are presented and analyzed in the context of the parameter space to show how FAST science achievements are affected. We summarize the scientific achievements of FAST and discuss its future science based on the new parts of the parameter space that can be explored by FAST.
Peng Jiang, Rurong Chen, Hengqian Gan, Jinghai Sun, Boqin Zhu, Hui Li, Weiwei Zhu, Jingwen Wu, Xuelei Chen, Haiyan Zhang, Tao An
Aug 23, 2024·astro-ph.IM·PDF The Five-hundred-meter Aperture Spherical Radio Telescope (FAST) Core Array is a proposed extension of FAST, integrating 24 secondary 40-m antennas implanted within 5 km of the FAST site. This original array design will combine the unprecedented sensitivity of FAST with a high angular resolution (4.3" at a frequency of 1.4 GHz), thereby exceeding the capabilities at similar frequencies of next-generation arrays such as the Square Kilometre Array Phase 1 or the next-generation Very Large Array. This article presents the technical specifications of the FAST Core Array, evaluates its potential relatively to existing radio telescope arrays, and describes its expected scientific prospects. The proposed array will be equipped with technologically advanced backend devices, such as real-time signal processing systems. A phased array feed receiver will be mounted on FAST to improve the survey efficiency of the FAST Core Array, whose broad frequency coverage and large field of view (FOV) will be essential to study transient cosmic phenomena such as fast radio bursts and gravitational wave events, to conduct surveys and resolve structures in neutral hydrogen galaxies, to monitor or detect pulsars, and to investigate exoplanetary systems. Finally, the FAST Core Array can strengthen China's major role in the global radio astronomy community, owing to a wide range of potential scientific applications from cosmology to exoplanet science.